Nuclear imaging to assess infarction, reperfusion, no-reflow, and viability
Thrombolytic therapy and primary percutaneous coronary have improved the survival of patients with acute myocardial infarction. However, this superior survival leads to an increased prevalence of left ventricular systolic dysfunction and development of heart failure at follow-up. Nuclear imaging permits comprehensive evaluation of patients with coronary artery disease. In the setting of acute myocardial infarction, <sup>99m</sup>Tc-sestamibi SPECT provides information on myocardium at risk, infarct size and myocardial salvage, well-known measures of the efficacy of reperfusion therapy, and important prognostic markers. In addition, nuclear imaging permits the assessment of no-reflow phenomenon that may take place during thrombolysis or percutaneous revascularization techniques. Timely detection of this phenomenon may help to select the most appropriate therapies to improve the microcirculation of the infarcted areas and, consequently, to improve the contractile function of the myocardium at follow-up. Furthermore, nuclear imaging plays a central role in the evaluation of ischemic heart failure patients with a substantial amount of dysfunctional but viable myocardium who may benefit from coronary revascularization with significant improvements in left ventricular function, heart failure symptoms, and prognosis. This chapter will review the role of nuclear imaging in acute myocardial infarction, with special focus on the relevance of this technique to assess the efficacy of reperfusion therapy. In addition, a detailed appraisal of multimodality imaging for noninvasive assessment of hibernating myocardium will be provided.